Are you trying to run gnome from another X server? You cannot run 2 xservers at once. Check those 2 files located at your /etc/X11/xinit
Depending how you login (graphical or text mode) you need to edit one or another. I edited Xclients because I use text login.
Check to see if you find PREFERRED=gnome-section as first choice there and it should do the trick
. If you login in graphical env. I think (I'm not sure) you'd to add exec gnome-section at the end of xinitrc
P.S: there are easiers ways to do this, but I cannot remember. However, it should still work